Alright Verizon and Samsung, I'm about to lose it here.
I have been using my Fascinate for the past 4 months to tether to my laptop. Out of nowhere, I connect my USB cord (factory original) and nothing happens. My computer is saying the USB device is not recognized, and although my phone is charging, it isn't connecting properly. The problem seems to be in the phone. Previously, when USB was connected to the computer, the USB debugging would launch, along with the other USB icon that says "select to mount/unmount device." Now, nothing happens. I have been in Applications-->Settings-->Development and turned on debugging. It still is not working. On the phone, I have checked for updates, closed all other programs, unmounted and remounted SD card, and reloaded tethering software. I even threw in a little pleading and cajoling. No dice. On the computer, I have checked the drivers, rebooted, closed other programs, disconnect/reconnect, and so on. Still no luck. I have searched the internet for the last two hours trying to find the solution, and I must be an idiot, because although I can find others with the problem, I can't find the solution.
I'm at my wit's end. If anyone could help, I would be very grateful.
The USB connection on the phone seems to be sensitive to how the connector is while connected. Although I haven't had this problem in a while, I remember when I first purchased this phone, I had to occasionally place something under the USB connector to keep the connection to the phone level.
The only reason I am suspecting this is the issue is because you were having a difficult time getting it to connect then all of a sudden it worked with no rhyme or reason.
The next time you have this problem, give it a try and see if this is the issue.